BlueTree BT-2000, Product Manual

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Chapter 4: Using the GPS Features
V1.5 BlueTree Wireless BT-2010 Product Manual 33
Chapter 4: Using the GPS Features
GPS Features
Overview
Your modem is equipped with a Trimble Lassen SQ™ GPS receiver
module that functions completely independently from the GPRS
wireless data component of the modem.
As long as the GPS receiver can detect satellite signals, you will be able
to obtain location information even when the modem is beyond GPRS
service coverage.
Hardware
The 8-channel parallel tracking GPS module is designed to operate with
the L1 frequency, standard position service, Coarse Acquisition code.
When connected to the external GPS antenna, the receiver will track up
to 8 GPS satellites and compute location, speed, heading and time.
The BT-2010 outputs the GPS location data through the unit’s auxiliary
port using TSIP (Trimble Standard Interface Protocol), TAIP (Trimble
ASCII Interface Protocol), and NMEA 0183 (National Marine Electronics
Association protocol).
Software
You can interact with the GPS receiver data one of two ways:
•
Using BlueVue as the functional and graphical interface
• Using Trimble GPS commands directly to the serial port
For comprehensive hardware and software reference information,
please see “GPS Reference” on page 65.
Power-Up and
Initialization
Although the GPS receiver functions independently from the data
modem, it does run on the same power supply, so it powers up at the
same time as the modem. The module does need to be fully initialized
to function properly.
Initializing the GPS
receiver the first time
To initialize the GPS receiver:
1.
Power-up the modem.
2.
Do not power down for at least 15 minutes.
The first time the GPS receiver is powered up, it searches for satellites
from a cold start because it has no almanac (database of available
satellites).
The receiver begins to compute position solutions within the first two
minutes, however the receiver must continuously track satellites for
approximately 15 minutes in order to download a complete almanac.
This initialization process should not be interrupted.
Everyday initialization
When the unit has completed its first initialization and established a
complete satellite almanac, the almanac data is stored in the unit’s
battery memory. In subsequent sessions, the time to first satellite fix
typically shortens to less than 45 seconds and the receiver will respond
to commands almost immediately after power-up.
Note: The GPS receiver is ready to accept TSIP commands approximately 2.1
seconds after power-up. If a command is sent to the receiver within this 2.1
second window, the receiver will ignore the commands.